Obesity is a chronic disease in which excess fat accumulation, that is, an abnormal build-up of body fat, raises the risk of adverse health outcomes. As with other chronic diseases, the definition does not require obesity-related complications to be present, and the condition carries social and psychological consequences alongside its medical ones.
The topic can be followed as a sequence of questions: how common obesity is, how excess fat is recognised and graded, why appetite control can fail, what the excess fat does to the body, and how it is treated.
- Obesity: Epidemiology and Prevalence — how common obesity is, how it varies by sex, race, education and income, and how prevalence has changed in adults and children in the USA and globally.
- Obesity: Measurement and Classification — how body fat is measured directly and indirectly, and how BMI (body mass index) and waist circumference are interpreted and classified.
- Obesity: Neurological Basis of Appetite Control — the homeostatic and reward circuits of hunger and satiety, and the hormonal signals that act on them.
- Obesity: Complications — the diseases obesity predisposes to, and why where the fat sits matters as much as how much there is.
- Obesity: Management — how obesity is treated, from lifestyle change through pharmacotherapy to bariatric surgery.
Begin with the epidemiology to see how widespread obesity has become, then the measurement to see how it is recognised at the bedside. The remaining notes then move from cause (appetite control) to consequence (complications) to treatment (management).